/Engine/Source/Editor/SubobjectEditor/Public/SSubobjectBlueprintEditor.h
Add a new subobject to the given parent via the subobject data subsystem
virtual [FSubobjectDataHandle](API\Editor\SubobjectDataInterface\FSubobjectDataHandle) AddNewSubobject ( const [FSubobjectDataHandle](API\Editor\SubobjectDataInterface\FSubobjectDataHandle) & ParentHandle, [UClass](API\Runtime\CoreUObject\UObject\UClass) * NewClass, [UObject](API\Runtime\CoreUObject\UObject\UObject) * AssetOverride, [FText](API\Runtime\Core\Internationalization\FText) & OutFailReason, [TUniquePtr](API\Runtime\Core\Templates\TUniquePtr)< [FScopedTransaction](API\Editor\UnrealEd\FScopedTransaction) > InOngoingTransaction )